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A Model for the Three Lepton Decay Mode of the Proton  [PDF]
Biswajoy Brahmachari,Patrick J. O'Donnell,Utpal Sarkar
Physics , 1994,
Abstract: An extension of the left--right symmetric model has been constructed which gives in a natural way the three lepton decay modes of the proton which have been suggested as an explanation for the atmospheric neutrino anomaly. We write down the potential which after minimization gives the proper choice of the Higgs spectrum. With this Higgs spectrum we then study the evolution of the gauge coupling constants and point out that for consistency one has to include effects of gravity.
Study of two- and three-meson decay modes of tau-lepton with Monte Carlo generator TAUOLA  [PDF]
Olga Shekhovtsova
Physics , 2015,
Abstract: The study of the $\tau$-lepton decays into hadrons has contributed to a better understanding of non-perturbative QCD and light-quark meson spectroscopy, as well as to the search of new physics beyond the Standard Model. The two- and three-meson decay modes, considering only those permitted by the Standard Model, are the predominant decays and together with the one-pion mode compose more than $85\%$ of the hadronic $\tau$-lepton decay width. In this note we review the theoretical results for these modes implemented in the Monte Carlo event generator TAUOLA and present at the same time a comparison with the Belle Collaboration data for the two-pion decay mode and the BaBar preliminary data for the three-pion decay mode as well for the decay mode into two-kaon and one-pion.
Proton decay and realistic models of quark and lepton masses  [PDF]
K. S. Babu,S. M. Barr
Physics , 1995, DOI: 10.1016/0370-2693(96)00536-9
Abstract: It is shown that in realistic SUSY GUT models of quark and lepton masses both the proton decay rate and branching ratios differ in general from those predicted in the minimal $SU(5)$ supersymmetric model. The observation of proton decay, and in particular the branching ratio $B[(p \rightarrow \pi^+ \overline{\nu})/(p \rightarrow K^+ \overline{\nu})]$, would thus allow decisive tests of these fermion mass schemes. It is shown that the charged lepton decay modes $p \rightarrow K^0 \mu^+, p \rightarrow K^0 e^+$ arising through gluino dressing diagrams are significant and comparable to the neutrino modes in large tan$\beta$ models. Moreover, it is found that in certain classes of models the Higgsino-mediated proton decay amplitudes are proportional to a model-dependent group-theoretical factor which in some cases can be quite small. The most interesting such class consists of $SO(10)$ models in which the dominant flavor-symmetric contribution to the up-quark mass matrix comes from an effective operator of the form ${\bf 16}_i{\bf 16}_j {\bf 10}_H {\bf 45}_H$, where $\langle {\bf 45}_H \rangle$ points approximately in the $I_{3R}$ direction. This class includes a recent model of quark and lepton masses proposed by the authors.
Suggested new modes in supersymmetric proton decay  [PDF]
K. S. Babu,J. C. Pati,F. Wilczek
Physics , 1997, DOI: 10.1016/S0370-2693(98)00108-7
Abstract: We show that in supersymmetric unified theories such as SO(10), implementation of the see-saw mechanism for neutrino masses introduces a new set of color triplet fields and thereby a new source of d=5 proton decay operators. For neutrino masses in a plausible range, these operators are found to have the right strength to yield observable, but not yet excluded, proton decay rates. The flavor structure of the new operators is distinctive. Proton decay modes into a charged lepton, such as l^+ \pi^0, l^+ K^0 and l^+ \eta where l = e or \mu, can become prominent, even for low or moderate values of tan(\beta) < 10, along with the \nu K^+ and \nu \pi^+ modes. A distinctive feature is the charged lepton modes involving an e^+ and/or a \mu^+ with the ratio \Gamma(l^+ K^0):\Gamma(l^+ \pi^0) = 2:1.
Search for Baryon and Lepton Number Violating Decays of the $τ$ Lepton  [PDF]
R. Godang
Physics , 1999, DOI: 10.1103/PhysRevD.59.091303
Abstract: We have searched for five decay modes of the tau lepton that simultaneously violate lepton and baryon number: tau -> anti-proton gamma, tau -> anti-proton pi0, tau -> anti-proton eta, tau -> anti-proton 2pi0, and tau -> anti-proton pi0eta. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The integrated luminosity of the data sample is 4.7 fb^{-1}, corresponding to the production of 4.3 x 10^6 tau+tau- events. No evidence is found for any of the decays, resulting in much improved upper limits on the branching fractions for the two-body decays and first upper limits for the three-body decays.
Family Symmetries and Proton Decay  [PDF]
Hitoshi Murayama,D. B. Kaplan
Physics , 1994, DOI: 10.1016/0370-2693(94)90242-9
Abstract: The proton decay modes $p\to K^0 e^+$ and $p\to K^0 \mu^+$ may be visible in certain supersymmetric theories, and if seen would provide evidence for new flavor physics at extremely short distances. These decay modes can arise from the dimension five operator $(Q_1Q_1Q_2L_{1,2})$, where $Q_i$ and $L_i$ are ${i^{th}}$ generation quark and lepton superfields respectively. Such an operator is not generated at observable levels due to gauge or Higgs boson exchange in a minimal GUT. However in theories that explain the fermion mass hierarchy, it may be generated at the Planck scale with a strength such that the decays $p\to K^0 \ell^+$ are both compatible with the proton lifetime and visible at Super-Kamiokande. Observable proton decay can even occur in theories without unification.
Giant Liquid Argon Observatory for Proton Decay, Neutrino Astrophysics and CP-violation in the Lepton Sector (GLACIER)  [PDF]
A. Badertscher,A. Curioni,U. Degunda,L. Epprecht,S. Horikawa,L. Knecht,C. Lazzaro,D. Lussi,A. Marchionni,G. Natterer,P. Otiougova,F. Resnati,A. Rubbia,C. Strabel,J. Ulbricht,T. Viant
Physics , 2009,
Abstract: GLACIER (Giant Liquid Argon Charge Imaging ExpeRiment) is a large underground observatory for proton decay search, neutrino astrophysics and CP-violation studies in the lepton sector. Possible underground sites are studied within the FP7 LAGUNA project (Europe) and along the JPARC neutrino beam in collaboration with KEK (Japan). The concept is scalable to very large masses.
Two- and Three-Body Decay Modes of SUSY Higgs Particles  [PDF]
A. Djouadi,J. Kalinowski,P. M. Zerwas
Physics , 1995,
Abstract: We summarize the dominant decay modes of the neutral and charged Higgs bosons in the Minimal Supersymmetric extension of the Standard Model. While two--body decays are in general dominating, the branching ratios for three--body decays of the heavy scalar, pseudoscalar and charged Higgs bosons can be large below the thresholds if top quarks, $W/Z$ bosons or heavy scalar bosons are involved. Analytical expressions have been derived for the partial decay widths and the physical implications of these decay modes are discussed.
Limits on tau Lepton-Flavor Violating Decays in three charged leptons  [PDF]
BaBar Collaboration,J. P. Lees
Physics , 2010, DOI: 10.1103/PhysRevD.81.111101
Abstract: A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using an integrated luminosity of 468 fb^-1 collected with the BABAR detector at the PEP-II collider. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (1.8-3.3) X 10^-8 at 90% confidence level.
\b{eta}-delayed three-proton decay of 31Ar  [PDF]
A. A. Lis,C. Mazzocchi,W. Dominik,Z. Janas,M. Pfützner,M. Pomorski,L. Acosta,S. Baraeva,E. Casarejos,J. Duénas-Díaz,V. Dunin,J. M. Espino,A. Estrade,F. Farinon,A. Fomichev,H. Geissel,A. Gorshkov,G. Kamiński,O. Kiselev,R. Kn?bel,S. Krupko,M. Kuich,Yu. A. Litvinov,G. Marquinez-Durán,I. Martel,I. Mukha,C. Nociforo,A. K. Ordúz,S. Pietri,A. Prochazka,A. M. Sánchez-Benítez,H. Simon,B. Sitar,R. Slepnev,M. Stanoiu,P. Strmen,I. Szarka,M. Takechi,Y. Tanaka,H. Weick,J. S. Winfield
Physics , 2015, DOI: 10.1103/PhysRevC.91.064309
Abstract: The beta decay of 31Ar, produced by fragmentation of a 36Ar beam at 880 MeV/nucleon, was investigated. Identified ions of 31Ar were stopped in a gaseous time projection chamber with optical readout allowing to record decay events with emission of protons. In addition to \b{eta}-delayed emission of one and two protons we have clearly observed the beta-delayed three-proton branch. The branching ratio for this channel in 31Ar is found to be 0.07(2)%.
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